Input apparatuses of mobile terminals such as mobile phones, for example, used by users to operate the terminals have been developed in a variety of manners according to functions and usages of each of the terminals. In many cases, the input apparatus is configured to allow the user to perform an operation input by directly pressing down a mechanical key or button disposed on a face of a body of the mobile terminal.
Such mechanical keys (for example, a numerical keypad) of the input apparatus of the terminal are normally preliminarily arranged based on a main usage of the terminal. Accordingly, such original arrangement of the mechanical keys may generally not be changed.
Incidentally, a variety of functions are incorporated in small mobile terminals, such as functions for a digital camera and a music player. For example, recent mobile terminals such as mobile phones have numerous supplementary functions incorporated therein in addition to a main function, and PDAs (Personal Digital Assistant: mobile information terminal) have a plurality of main usages such as schedule management, an address book and the like. With the keys of such terminals fixedly arranged, the user may feel significantly inconvenient in using some functions.
In order to solve such inconvenience in operation input, there is disclosed an input apparatus having a touch panel constituted by using a transparent input unit arranged on top of a liquid crystal display constituting a display unit (for example, see Patent Document 1). The input apparatus having such a touch panel generally displays graphical images of operation keys and buttons (hereinafter, referred to as an “object”) for the input operation on a display screen of the touch panel. When the user presses the object displayed on the display screen, the input unit receives an input at a corresponding position on the touch panel.
Since the input apparatus having the touch panel receives an input in the form of a user's direct contact (touch) to the object displayed on the display unit, the user may perform the input operation highly intuitively. That is, the user operates the input apparatus at the fingertip and the like by directly touching the object displayed on the display screen, following a guide displayed on the display screen of the touch panel. Accordingly, the user may operate the terminal extremely easily by an intuitive operation following the navigation displayed on the display screen, which offers an effect to reduce erroneous operations as a result.
As described above, since the touch panel increases a freedom of configuration of the input unit and allows the user to perform the operation input fairly instinctively, terminal apparatuses having the input apparatus with the touch panel have become more popular.
Incidentally, in order to further improve operability of the touch panel, there is suggested an input apparatus that has a load detection unit for detecting a pressure of a pressing operation to the touch panel and may receive an input based on the pressure load of an input by the user (for example, see Patent Document 2). This input apparatus may control not to receive the input unless the pressure on the touch panel is equal to or over a certain value. This input apparatus, accordingly, may prevent the erroneous operation to receive the input when the user lightly touches the touch panel inadvertently.